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I don't completely agree...

about the feedback issue. In the end it just becomes a matter of semantics, but to me there is a distinction between a follower and a Sziklai pair (or any other feedback configuration for that matter). The word "feedback" clearly implies that the signal is being "fed" from one point in the circuit "back" to a point earlier in the circuit. This does not happen with a follower (or when using an unbypassed resistor in the emitter/source/cathode of a common-emitter/source/cathode gain stage).

I hear a clear difference in sonic performance between the feedback in a loop (no matter how short) and the "feedback" in a follower. A much more precise way to talk about this distinction is to call the loss of gain that occurs in a follower "degeneration". Although the reduction in gain is the same, the mechanism and the sonic result are quite different.

Regarding the FETs, I would second Curl's recommendation of the 2SK213. It is basically a 1/4 size version of the 2SK1058. The only problem with this part is that the P-channel complement kind of sucks, and Semelab does not make a clone of this part. If you are not using complementary circuits, this is not an issue.

A "hexfet" is just IR's trademark for a hexagonal structure on the die of their vertical MOSFETs. Every modern MOSFET is built in either this or some similar way that minimizes the on-resistance. This is critical for switching applications, but is not very good for audio. I would replace these. By the way, the P-channel IR brand parts are extremely non-linear and really suck for audio.

The problem with AC coupling is that the capacitors color the sound so much. Good sounding 100 uF caps are *extremely* expensive and large. Plus you have to do a bunch of listening tests to find out which ones are good. It might be a quick way to get started, though.

Best regards,
Charles Hansen

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